The background of the invention relates to the so-called Macondo-blowout, which was initiated in April, 2010. The blowout originated from a BP-operated oil well located in ca. 1500 meter deep water in the Gulf of Mexico. Following a preceding explosion on a floating drilling rig (“Deepwater Horizon”) connected to the oil well, attempts were made to sever an associated oil pipe extending through a blowout preventer placed on the seabed above the oil well. High pressure from flowing oil in the oil pipe caused the pipe to bend and displace to a non-centric position within the through bore (pipe interior) of the blowout preventer. Among other things, this blowout preventer was provided with a so-called blind shear ram designed for severing a steel pipe and also for subsequent sealing of the bore through the blowout preventer. The shear ram, however, was not designed for severing a non-centric pipe in the blowout preventer. This resulted in incomplete severing and sealing of the bore of the blowout preventer, whereby oil at high pressure leaked out for a long time thereafter.